This Workout Gear Is Fashionable Enough for the Runway

There is a growing conflation of what you may wear for a workout and the ready-to-wear clothes on the runways of Milan and Paris. The designer Gosha Rubchinskiy, who has collaborated with the Italian sportswear company Kappa, and Vetements, which has worked with Reebok, have been leading the charge. And with sports-centric brands like Tracksmith, Soar and Outdoor Voices also offering chic versions of activewear, who’s to say what’s appropriate for the gym and what’s better left to more fashionable occasions?